EP4030573A1 - Dispositif, système et procédé pour effectuer une mise à jour en ligne d'un équivalent à deux ports - Google Patents

Dispositif, système et procédé pour effectuer une mise à jour en ligne d'un équivalent à deux ports Download PDF

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Publication number
EP4030573A1
EP4030573A1 EP21160638.9A EP21160638A EP4030573A1 EP 4030573 A1 EP4030573 A1 EP 4030573A1 EP 21160638 A EP21160638 A EP 21160638A EP 4030573 A1 EP4030573 A1 EP 4030573A1
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EP
European Patent Office
Prior art keywords
bus
line
impedances
trip
updated
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Pending
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EP21160638.9A
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German (de)
English (en)
Inventor
Vedanta PRADHAN
Od Naidu
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Hitachi Energy Ltd
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Hitachi Energy Switzerland AG
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Publication of EP4030573A1 publication Critical patent/EP4030573A1/fr
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/006—Calibration or setting of parameters
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
    • G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
    • G01R27/16—Measuring impedance of element or network through which a current is passing from another source, e.g. cable, power line
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
    • H02H7/261—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured involving signal transmission between at least two stations
    • H02H7/263—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured involving signal transmission between at least two stations involving transmissions of measured values
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
    • G06F17/10—Complex mathematical operations
    • G06F17/11—Complex mathematical operations for solving equations, e.g. nonlinear equations, general mathematical optimization problems
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
    • G06F17/10—Complex mathematical operations
    • G06F17/16—Matrix or vector computation, e.g. matrix-matrix or matrix-vector multiplication, matrix factorization
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H1/00—Details of emergency protective circuit arrangements
    • H02H1/0007—Details of emergency protective circuit arrangements concerning the detecting means
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H1/00—Details of emergency protective circuit arrangements
    • H02H1/0061—Details of emergency protective circuit arrangements concerning transmission of signals
    • H02H1/0084—Details of emergency protective circuit arrangements concerning transmission of signals by means of pilot wires or a telephone network; watching of these wires
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H1/00—Details of emergency protective circuit arrangements
    • H02H1/0092—Details of emergency protective circuit arrangements concerning the data processing means, e.g. expert systems, neural networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/22—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for distribution gear, e.g. bus-bar systems; for switching devices
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
    • H02H7/261—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured involving signal transmission between at least two stations
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J13/00—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network
    • H02J13/00002—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network characterised by monitoring
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J13/00—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network
    • H02J13/00006—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network characterised by information or instructions transport means between the monitoring, controlling or managing units and monitored, controlled or operated power network element or electrical equipment
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J13/00—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network
    • H02J13/00006—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network characterised by information or instructions transport means between the monitoring, controlling or managing units and monitored, controlled or operated power network element or electrical equipment
    • H02J13/00016—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network characterised by information or instructions transport means between the monitoring, controlling or managing units and monitored, controlled or operated power network element or electrical equipment using a wired telecommunication network or a data transmission bus
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J13/00—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network
    • H02J13/00006—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network characterised by information or instructions transport means between the monitoring, controlling or managing units and monitored, controlled or operated power network element or electrical equipment
    • H02J13/00028—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network characterised by information or instructions transport means between the monitoring, controlling or managing units and monitored, controlled or operated power network element or electrical equipment involving the use of Internet protocols
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/25—Arrangements for measuring currents or voltages or for indicating presence or sign thereof using digital measurement techniques
    • G01R19/2513—Arrangements for monitoring electric power systems, e.g. power lines or loads; Logging
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
    • H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]

Definitions

  • the invention relates to power transmission systems and devices and methods for protecting power transmission systems.
  • the invention relates in particular to methods and devices that are operative to update one or several equivalent impedances of a two-port equivalent across a transmission line that can be used for various protection, control, or coordination functions.
  • each such line is connected to the rest of the network through other transmission lines.
  • shunt elements such as a reactor or capacitor may also be connected at buses.
  • FIG. 2 An equivalent model of the system is shown in Fig. 2 , in which all components of the system (except the line of concern) are captured in a two-port Thevenin equivalent.
  • the equivalent system has two sources with corresponding impedances Z sM and Z sN . Additionally, a transfer path with impedance Z tr MN may be present which represents equivalent of the electric power system for current flow between buses M and N except for a direct path through the branch MN itself.
  • the two-port Thevenin equivalent can be calculated if the full network topology and/or the network impedance matrix, i.e., Z BUS are available as an input.
  • a short circuit analysis based on the complete network information can yield the two-port equivalent parameters of any particular line of interest. While such a technique could be employed when the system topology changes, the required information for re-calculating the two-port Thevenin equivalent is often not available at, e.g., a substation level.
  • the equivalent model be updated at a substation level (in a decentralized manner) using only the process bus information without depending on repetitive updates from the central control center of the grid.
  • information of the entire network topology and topology updates from all over the system may not be available at a substation level. Therefore, a complete network analysis (CNA) may not be a viable option for execution at substation device.
  • CNA network analysis
  • a source impedance can be estimated by calculating a ratio of bus voltage drop from nominal value to the change in current seen by the source.
  • Such techniques typically address the limited problem of obtaining source impedance as seen by a protective relay placed at a terminal of the line. Moreover, they also face the challenge that a fault must be created in the system during normal operation.
  • US 8 050 878 B2 discloses device and method for dynamically determining an impedance of a network.
  • the device includes at least a processing system for measuring a network voltage and network current when said network is determined to be in a first state, measuring a network voltage when said network is determined to be in a second state, estimating the impedance value dependent upon said measured voltages and current, adapting the estimated impedance based on at least one prior impedance value and storing at least the adapted impedance.
  • devices, systems, and methods are provided that afford an online update of the two-port equivalent.
  • Such an online update may be performed responsive to a trip event.
  • the online update can facilitate adaptive setting of relays which can thereby improve its dependability and security.
  • the devices, systems, and methods require information from only a neighborhood of substation level measurements.
  • the devices, systems, and methods can be implemented at the substation level, without requiring an update from a control center.
  • the devices, systems, and methods provide an online update of the two-port equivalent that can be used in various protection applications and adds value to digital substation solutions.
  • the devices, systems, and methods use information of lines and buses adjacent to the line of interest, i.e., network information of the adjacent topology, to update the two-port equivalent model across the line of interest.
  • the effect of topology changes in the neighborhood of the line of interest can be accounted for by updating its two-port equivalent.
  • the devices, systems, and methods are operative to perform an online update of the two-port equivalent across a transmission line using substation process bus data in response to a topology change limited to one level up in network topology.
  • the devices, systems, and methods are operative to perform an online update of the two-port equivalent in response to at least following types of network topology changes:
  • the devices, systems, and methods may be operative to update a network impedance submatrix without depending on the full network topology or full network impedance matrix. Rather, only information such as the initial equivalent parameters, parameters of the transmission line of interest and a tripping element (such as a second line or a shunt element at an adjacent bus) and a limited amount of voltage measurements and, optionally, current measurements are used in estimating the network impedance submatrix thus, making the techniques suitable for being performed at the substation level.
  • the parameters used may specifically include or be the impedances of a fundamental frequency model representation of the transmission line of interest and tripping element (such as a second line or a shunt element at an adjacent bus).
  • Embodiments of the present invention update the equivalent in response to topological changes (as described in the disclosure), by using the initial equivalent and voltage and/or current measurements related to the topology event, which is determined by breaker/switch status inputs of the switched component(s).
  • This is a significant departure from the techniques of " POWER SWING AND OUT-OF-STEP CONSIDERATIONS ON TRANSMISSION LINES", IEEE PSRC WG D6, 2005 , J. Mooney and J. Peer, "Application Guidelines for Ground Fault Protection," proceedings of the 24th Annual Western Protective Relay Conference, Spokane, WA, October 1997 , and M. J. Thomson and A. Somani, “A tutorial on Calculating Source Impedance Ratios for Determining Line Length”, SEL, 2015 , which need to be re-applied each time a topology event occurs by discarding the previous equivalent data.
  • a device or system for use with an electric power system has a first bus, a second bus, a third bus, a first line between the first and second buses, and a second line between the third bus and one of the first and second buses.
  • the device or system comprises an interface to receive measurements comprising voltage measurements for one or several of the buses and to receive switch status information.
  • the device or system is operative to determine, responsive to at least one trip event, one or several updated impedances of an equivalent model from the received measurements and impedances of the equivalent model obtained before the at least one trip event.
  • the device or system may be operative to use model parameters of the first line and at least one of the second line or a shunt element which trips for determining the updated impedances.
  • the interface may be operative to receive current measurements.
  • the interface may be operative to receive current measurements for at least one of the first and second lines or for at least one shunt element.
  • the device or system may be operative to perform an online update of the equivalent model during field operation, by determining the one or several updated impedances.
  • the device or system may be operative such that all measurements and, optionally, the switch status information used for determining the one or several updated impedances of the equivalent model may be obtained in a neighborhood of the first line.
  • the neighborhood of the first line from which measurements are used for determining the updated impedances may include the first and second lines, the first, second, and third buses, and shunt elements connected thereto, including associated switches and/or circuit breakers.
  • the device or system may be operative such that all measurements and, optionally, the switch status information used for determining the one or several updated impedances of the equivalent model are obtained from a neighborhood of the first line that includes the first and second lines, the first, second, and third buses, and shunt elements connected thereto, including associated switches and/or circuit breakers.
  • the device or system may be operative to determine the updated impedances of the equivalent model without requiring measurements other than measurements obtained from a neighborhood of the first line that includes the first and second lines, the first, second, and third buses, and shunt elements connected thereto, including associated switches and/or circuit breakers.
  • the device or system may be operative to receive the measurements (such as voltage and/or current measurements) and/or switch status information via a substation automation communication network.
  • the device or system may be operative to receive the measurements and/or switch status information in messages in accordance with a substation automation communication protocol.
  • the device or system may be operative to receive the measurements and/or switch status information in messages in accordance with a substation automation communication protocol.
  • the device or system may be operative to receive the measurements and/or switch status information in messages in accordance with or compatible with IEC 61850.
  • the device or system may be operative to receive the measurements and/or switch status information in messages in accordance with or compatible with IEC 61850:8-1, IEC 61850:8-2, and/or IEC 61850:9.
  • the device or system may be operative to receive the measurements and/or switch status information in messages in accordance with or compatible with IEC 61850:8-1 (2011), IEC 61850:8-2 (2016), and/or IEC 61850:9 (2011) and/or IEC 61850:9/AMD1:2020 (2020).
  • the device or system may be operative such that all measurements and, optionally, the switch status information used for determining the one or several updated impedances of the equivalent model may be substation process bus level measurements.
  • the switch status information may be or may comprise measurements of switch state (such as tripped or untripped).
  • the switch status information may be or may comprise messages transmitted by at least one intelligent electronic device, IED and indicative a current or imminent switch state (such as tripped or untripped).
  • the switch status information may be obtained by analyzing messages transmitted by at least one IED.
  • the messages may be GOOSE messages or other messages in accordance with IEC 61850.
  • the switch status information may include information indicative of a trip of a switch on the line incident upon one of the terminal buses of the line of interest.
  • the switch status information may include information indicative of a trip of a shunt element connected at a bus adjacent the terminal buses of the line of interest.
  • the at least one trip event may be detected based on the switch status information and, more particularly, based on a change in switch status (e.g., from untripped to tripped).
  • the one or several updated impedances of the equivalent model may be updated impedances of a two-port equivalent across the first line subsequent to the at least one trip event.
  • the impedances of the equivalent model obtained before the at least one trip event may comprise base impedances of the equivalent model of the two-port equivalent prior to the at least one trip event.
  • the device or system may be operative to perform at least one protection function using the updated impedances of the equivalent model.
  • the device or system may be operative to use the updated impedances of the equivalent model for at least one of:
  • the updated impedances of the equivalent model may comprise an updated first equivalent source impedance, an updated second equivalent source impedance, and an updated equivalent transfer path impedance.
  • the device or system may be operative to determine at least one matrix element of an impedance submatrix using the measurements, perform series and/or shunt branch modifications of the impedance submatrix to determine matrix elements of a modified impedance submatrix, and determine the updated impedances of the equivalent model of the two-port equivalent using the modified impedance submatrix.
  • the device or system may be operative to determine at least one matrix element of a bus impedance submatrix using the measurements, perform series and/or shunt branch modifications of the bus impedance submatrix to determine matrix elements of a modified bus impedance submatrix, and determine the updated impedances of the equivalent model of the two-port equivalent using the modified bus impedance submatrix.
  • the device or system may be operative to determine at least Z mm , Z mn , Z nm , and Z nn from impedances of the equivalent model of the two-port equivalent obtained before the at least one trip event and modification calculations.
  • the device or system may be operative to determine the one or several updated impedances of the equivalent model responsive to a trip of the second line.
  • the device or system may be operative to determine the one or several updated impedances of the equivalent model responsive to a trip of the second line using measurements of a change in voltage at the second bus in response to the trip of the second line and a current on the second line at the first bus before the trip of the second line (which may be measured or calculated) and a charging current of the second line before the trip of the second line (which is calculated).
  • the device or system may be operative to determine the one or several updated impedances of the equivalent model using the following additional quantities obtained from measurements (which encompasses quantities derived computationally from measurements): (i) changes in voltages at the first and third buses in response to the trip of the second line; or (ii) a current of the second line at first bus before the trip of the second line.
  • the device or system may be operative to determine the one or several updated impedances of the equivalent model responsive to a trip of the second line using only measurements of a change in voltage at the second bus in response to the trip of the second line and a current on the second line at the first bus before the trip of the second line (which may be measured or calculated) and (i) changes in voltages at the first and third buses in response to the trip of the second line (which may be measured or computationally derived from measurements); or (ii) a current of the second line at first bus before the trip of the second line (which may be measured or computationally derived from measurements).
  • the device or system may be operative to determine I mp + I mc from a current measurement.
  • the device or system may be operative to determine at least Z mp , Z pm . and Z pp by using impedances of the equivalent model of the two-port equivalent obtained before the at least one trip event and modification calculations.
  • the device or system may be operative to determine at least Z mp , Z pm . and Z pp using the measurements.
  • the device or system may be operative to determine I mp + I mc from a current measurement.
  • the device or system may be operative to determine the one or several updated impedances of the equivalent model responsive to a trip of a shunt element at the third bus.
  • the device or system may be operative to determine the one or several updated impedances of the equivalent model responsive to a trip of a shunt element at the third bus using a shunt current through the shunt element at the third bus prior to the trip of the shunt element (which may be measured or computationally derived from measurements) and a change in voltage at the second bus in response to the trip of the shunt element (which may be measured or computationally derived from measurements).
  • the device or system may be operative to determine the one or several updated impedances of the equivalent model responsive to a trip of a shunt element at the third bus using only the following quantities included in or computationally derived from measurements: a shunt current through the shunt element at the third bus prior to the trip of the shunt element and a change in voltage at the second bus in response to the trip of the shunt element.
  • the device or system may be operative to determine the one or several updated impedances of the equivalent model responsive to a trip of a shunt element at the third bus further using changes in voltages at the first and third buses in response to the trip of the shunt element (which may be measured or computationally derived from measurements).
  • the device or system may be operative to determine the one or several updated impedances of the equivalent model responsive to a trip of a shunt element at the third bus using only the following quantities included in or computationally derived from measurements (it being noted that the other quantities used do not need to be determined from measurements in field operation): a shunt current through the shunt element at the third bus prior to the trip of the shunt element and a change in voltage at the second bus in response to the trip of the shunt element and measurements of changes in voltages at the first and third buses in response to the trip of the shunt element.
  • the device or system may be operative to obtain I p sh from a shunt current measurement prior to the trip of the shunt element.
  • the device or system may be operative to determine at least Z mp , Z pm . and Z pp by using impedances of the equivalent model of the two-port equivalent obtained before the at least one trip event and modification calculations.
  • the device or system may be operative to determine at least Z mp , Z pm , and Z pp using the measurements.
  • the device or system may be operative to obtain I p sh from a shunt current measurement prior to the trip of the shunt element.
  • the device or system may be operative to determine the one or several updated impedances of the equivalent model responsive to at least one of:
  • the device or system may comprise at least one integrated circuit coupled to the interface and operative to determine the at least one updated impedance of the equivalent model.
  • the interface may be operative for communicative coupling to a substation bus.
  • the device or system may comprise a storage device to store the impedances of the equivalent model and/or bus impedance submatrix elements obtained before the at least one trip event.
  • the device or system may be operative for communicative coupling to a storage device to retrieve the impedances of the equivalent model and/or bus impedance submatrix elements obtained before the at least one trip event from the storage device.
  • the device or system may be a substation device or substation system, such as a substation computer.
  • An electric power system comprises a first bus, a second bus, a third bus, a first line between the first and second buses, a second line between the third bus and one of the first and second buses, and the device or system according to any embodiment to determine updated impedances of the equivalent model of a two-port equivalent from the received measurements and impedances of the equivalent model obtained before the at least one trip event.
  • the device or system may be operative to use model parameters of the first line and at least one of the second line or a shunt element which trips for determining the updated impedances.
  • the device or system may be a protection or coordination system operative to perform at least one protection or coordination function using the updated impedances of the equivalent model.
  • the electric power system may comprise a protection or coordination system communicatively coupled to the device or system, the protection or coordination system being operative to perform at least one protection or coordination function using the updated impedances of the equivalent model.
  • the device or system may be operative to determine the one or several updated impedances of the equivalent model of the two-port equivalent across the first line responsive to a trip of the second line.
  • the electric power system may comprise a shunt element at the third bus.
  • the device or system may be operative to determine the one or several updated impedances of the equivalent model of the two-port equivalent across the first line responsive to a trip of the shunt element.
  • the device or system that is operative to determine the updated impedances of the equivalent model is a substation device or a substation system.
  • An electric power system may comprise a plurality of substations, each comprising a substation device or system operative to determine updated impedances of a two-port equivalent model.
  • the device or system operative to determine updated impedances may respectively be a device or system according to an embodiment.
  • the electric power system may comprise a central entity communicatively coupled to the substation devices or systems and operative to coordinate the substation devices or systems and/or to combine updated impedances obtained from different substation devices or system.
  • the substation devices or systems may be operative to update equivalent impedances independently of each other.
  • a first substation device or system may be operative to update impedances using measurements of the substation and, optionally, an adjacent bus and incident line responsive to a first trip event.
  • a time at which the first substation device or system determines the updated impedances may be independent of a time at which any of the other substation devices or system (e.g., a second substation device or system of a second substation and/or a third substation device or system of a third substation) determines updated impedances.
  • a second substation device or system may be operative to update impedances using measurements of the substation and, optionally, an adjacent bus and incident line responsive to a second trip event.
  • a time at which the second substation device or system determines the updated impedances may be independent of a time at which any of the other substation devices or system (e.g., the first substation device or system of the second substation and/or a third substation device or system of a third substation) determines updated impedances.
  • the impedances of the first, second and, if present, additional substation devices or systems as updated during field operation may be updated at times and/or to values that are independent of each other.
  • the central entity may be operative to receive updated impedances from the substation devices or systems.
  • the central entity may be operative to combine updated impedances from the substation devices or systems.
  • the central entity may be operative to update a bus matrix, using the updated impedances from the substation devices or systems.
  • the central entity may be operative to coordinate operation of the substation devices or systems of different substations.
  • the central entity may be a central controller.
  • the central entity and/or the substation devices or systems may be operative to use the updated impedances for analyses, protection and/or coordination functions.
  • the central entity and/or the substation devices or systems may be operative to use the updated impedances for one or several of: setting operational characteristics of a distance relay, setting power swing blinders and/or out of step logic, locating a fault on the line when using only single ended measurements.
  • a method of determining updated impedances of an equivalent model across a transmission line for an electric power system is provided.
  • the electric power system having a first bus, a second bus, a third bus, a first line between the first and second buses, and a second line between the third bus and one of the first and second buses.
  • the method comprises receiving, by a device or system, measurements comprising voltage measurements for one or several of the buses and switch status information.
  • the method comprises determining, by the device or system, responsive to at least one trip event, one or several updated impedances of the equivalent model from the received measurements and impedances of the equivalent model obtained before the at least one trip event.
  • an online update of the equivalent model may be performed during field operation, by determining the one or several updated impedances.
  • model parameters of the first line and at least one of the second line or a shunt element which trips for determining the updated impedances.
  • the measurements may comprise current measurements.
  • the current measurements may comprise current measurements for at least one of the first and second lines or for at least one shunt element.
  • All measurements and, optionally, the switch status information used for determining the one or several updated impedances of the equivalent model may be obtained in a neighborhood of the first line.
  • All measurements and, optionally, the switch status information used for determining the one or several updated impedances of the equivalent model may be substation process bus level measurements.
  • the neighborhood of the first line from which measurements are used for determining the updated impedances may include the first and second lines, the first, second, and third buses, and shunt elements connected thereto, including associated switches and/or circuit breakers.
  • All measurements and, optionally, the switch status information used for determining the one or several updated impedances of the equivalent model may be obtained from a neighborhood of the first line that includes the first and second lines, the first, second, and third buses, and shunt elements connected thereto, including associated switches and/or circuit breakers.
  • the updated impedances of the equivalent model may be determined without requiring measurements other than measurements obtained from a neighborhood of the first line that includes the first and second lines, the first, second, and third buses, and shunt elements connected thereto, including associated switches and/or circuit breakers.
  • the measurements (such as voltage and/or current measurements) and/or switch status information may be received via a substation automation communication network.
  • the measurements and/or switch status information may be received in messages in accordance with a substation automation communication protocol.
  • the measurements and/or switch status information may be received in messages in accordance with a substation automation communication protocol.
  • the measurements and/or switch status information may be received in messages in accordance with or compatible with IEC 61850.
  • the measurements and/or switch status information may be received in messages in accordance with or compatible with IEC 61850:8-1, IEC 61850:8-2, and/or IEC 61850:9.
  • the measurements and/or switch status information may be received in messages in accordance with or compatible with IEC 61850:8-1 (2011), IEC 61850:8-2 (2016), and/or IEC 61850:9 (2011) and/or IEC 61850:9/AMD1:2020 (2020).
  • the switch status information may be or may comprise measurements of switch state (such as tripped or untripped).
  • the switch status information may be or may comprise messages transmitted by at least one intelligent electronic device, IED and indicative a current or imminent switch state (such as tripped or untripped).
  • the switch status information may be obtained by analyzing messages transmitted by at least one IED.
  • the messages may be GOOSE messages or other messages in accordance with IEC 61850.
  • the switch status information may include information indicative of a trip of a switch on the line incident upon one of the terminal buses of the line of interest.
  • the switch status information may include information indicative of a trip of a shunt element connected at a bus adjacent the terminal buses of the line of interest.
  • the at least one trip event may be detected based on the switch status information and, more particularly, based on a change in switch status (e.g., from untripped to tripped).
  • the one or several updated impedances of the equivalent model may be updated impedances of a two-port equivalent across the first line subsequent to the at least one trip event.
  • the impedances of the equivalent model obtained before the at least one trip event may comprise impedances of the equivalent model of the two-port equivalent prior to the at least one trip event.
  • the updated impedances of the equivalent model may comprise an updated first equivalent source impedance, an updated second equivalent source impedance, and an updated equivalent transfer path impedance.
  • the method may comprise determining at least one matrix element of an impedance submatrix using the measurements, performing series and/or shunt branch modifications of the impedance submatrix to determine matrix elements of a modified impedance submatrix, and determining the updated impedances of the equivalent model of the two-port equivalent using the modified impedance submatrix.
  • the method may comprise determining at least one matrix element of a bus impedance submatrix using the measurements, performing series and/or shunt branch modifications of the bus impedance submatrix to determine matrix elements of a modified bus impedance submatrix, and determining the updated impedances of the equivalent model of the two-port equivalent using the modified bus impedance submatrix.
  • At least Z mm , Z mn , Z nm , and Z nn may be determined from impedances of the equivalent model of the two-port equivalent obtained before the at least one trip event and modification calculations.
  • the method may comprise determining the one or several updated impedances of the equivalent model responsive to a trip of the second line.
  • the device or system may determine the one or several updated impedances of the equivalent model responsive to a trip of the second line using measurements of a change in voltage at the second bus in response to the trip of the second line and a current on the second line at the first bus before the trip of the second line (which may be measured or calculated) and a charging current of the second line before the trip of the second line (which is calculated).
  • the method may comprise determining using the following additional quantities obtained from measurements (which encompasses quantities derived computationally from measurements): (i) changes in voltages at the first and third buses in response to the trip of the second line; or (ii) a current of the second line at first bus before the trip of the second line.
  • the method may comprise determining the one or several updated impedances of the equivalent model responsive to a trip of the second line using only measurements of a change in voltage at the second bus in response to the trip of the second line and a current on the second line at the first bus before the trip of the second line (which may be measured or calculated) and (i) changes in voltages at the first and third buses in response to the trip of the second line (which may be measured or computationally derived from measurements); or (ii) a current of the second line at first bus before the trip of the second line (which may be measured or computationally derived from measurements).
  • the method may comprise determining I mp + I mc from a current measurement.
  • the method may comprise determining at least Z mp , Z pm , and Z pp by using impedances of the equivalent model of the two-port equivalent obtained before the at least one trip event and modification calculations.
  • the method may comprise determining at least Z mp , Z pm . and Z pp using the measurements.
  • the method may comprise determining I mp + I mc from a current measurement.
  • the method may comprise determining the one or several updated impedances of the equivalent model responsive to a trip of a shunt element at the third bus.
  • the method may comprise determining the one or several updated impedances of the equivalent model responsive to a trip of a shunt element at the third bus using a shunt current through the shunt element at the third bus prior to the trip of the shunt element (which may be measured or computationally derived from measurements) and a change in voltage at the second bus in response to the trip of the shunt element (which may be measured or computationally derived from measurements).
  • the method may comprise determining the one or several updated impedances of the equivalent model responsive to a trip of a shunt element at the third bus using only the following quantities included in or computationally derived from measurements (it being noted that the other quantities used do not need to be determined from measurements in field operation): a shunt current through the shunt element at the third bus prior to the trip of the shunt element and a change in voltage at the second bus in response to the trip of the shunt element.
  • the method may comprise determining the one or several updated impedances of the equivalent model responsive to a trip of a shunt element at the third bus further using changes in voltages at the first and third buses in response to the trip of the shunt element (which may be measured or computationally derived from measurements).
  • the method may comprise determining the one or several updated impedances of the equivalent model responsive to a trip of a shunt element at the third bus using only the following quantities included in or computationally derived from measurements (it being noted that the other quantities used do not need to be determined from measurements in field operation):a shunt current through the shunt element at the third bus prior to the trip of the shunt element (which may be obtained from a current measurement or determined computationally from a voltage measurement) and a change in voltage at the second bus in response to the trip of the shunt element and measurements of changes in voltages at the first and third buses in response to the trip of the shunt element.
  • the method may comprise determining I p sh from a shunt current measurement prior to the trip of the shunt element.
  • the method may comprise determining at least Z mp , Z pm , and Z pp by using impedances of the equivalent model of the two-port equivalent obtained before the at least one trip event and modification calculations.
  • the method may comprise determining at least Z mp , Z pm . and Z pp using the measurements.
  • the method may comprise determining I p sh from a shunt current measurement prior to the trip of the shunt element.
  • the method may comprise determining the one or several updated impedances of the equivalent model responsive to at least one of:
  • the device or system may comprise at least one integrated circuit coupled to the interface and which determines the at least one updated impedance of the equivalent model.
  • the interface may be communicatively coupled to a substation bus.
  • Impedances of the equivalent model and/or bus impedance submatrix elements obtained before the at least one trip event may be retrieved from a storage device.
  • the storage device may be integrated in the device or system that determines the updated impedances of the equivalent model or separate therefrom.
  • the device or system may be a substation device or substation system, such as a substation computer.
  • a method of performing at least one protection function may comprise determining the updated impedances of the equivalent model using the method of an embodiment and using the updated impedances of the equivalent model.
  • the updated impedances of the equivalent model may be used for at least one of:
  • the device or system carrying out the method may be a protection or coordination system operative to perform at least one protection or coordination function using the updated impedances of the equivalent model.
  • the device or system carrying out the method may determine the one or several updated impedances of the equivalent model of the two-port equivalent across the first line responsive to a trip of the second line.
  • the device or system carrying out the method may determine the one or several updated impedances of the equivalent model of the two-port equivalent across the first line responsive to a trip of a shunt element at the third bus.
  • instruction code executable by at least one processing device, in particular at least one integrated circuit of a digital substation device or a digital substation system, that causes the at least one processing device to automatically perform the method according to any embodiment.
  • a storage medium having stored thereon instruction code executable by at least one processing device, in particular at least one integrated circuit of a digital substation device or a digital substation system, that causes the at least one processing device to automatically perform the method according to any embodiment.
  • the storage medium may be a non-transitory storage medium.
  • the devices, systems, and methods allow substation and/or process bus data at the line terminals and buses one level up in the topology to be used to determine updated equivalent impedances.
  • the data may be obtained using measurement and communication infrastructure in digital substations.
  • the devices, systems, and methods allow updating of equivalent impedances to be performed for topological events such as incident line trip and shunt element trip at an adjacent bus.
  • the devices, systems, and methods do not require information of short circuit levels of the terminal buses and fault current contributions from the line of concern itself to determine the updated impedances of the equivalent model.
  • the devices, systems, and methods do not require information on staged bus faults to determine the updated impedances of the equivalent model.
  • the devices, systems, and methods do not require information on the entire network topology information to determine the updated impedances of the equivalent model.
  • the devices, systems, and methods afford simple and non-iterative implementation of the determination of the updated impedances of the equivalent model.
  • the devices, systems, and methods may be operative to use information such as the base equivalent parameters, parameters of the transmission line of interest and a tripping element (such as a second line or a shunt element at an adjacent bus) and a limited amount of voltage measurements and, optionally, current measurements in estimating an impedance submatrix thus, making the techniques suitable for the substation level.
  • the parameters used may specifically include or be the impedances of a fundamental frequency model representation of the transmission line of interest and tripping element (such as a second line or a shunt element at an adjacent bus).
  • the devices, methods, and systems according to embodiments can be used in association with a three-phase transmission system, in particular for a grid having renewable energy source.
  • devices, systems, and methods are provided that are operative to perform an online update of impedances of an equivalent model (also referred to as "equivalent impedances" herein).
  • the devices, systems, and methods may be operative to perform an online update of equivalent impedances of a two-port Thevenin equivalent across a transmission line.
  • the devices, systems, and methods are operative to determine updated impedances (such as two updated source impedances and an updated transfer path impedance in the two-port Thevenin equivalent across a transmission line) in response to at least following types of network topology changes:
  • the devices, systems, and methods are operative to perform the online update by using information on impedances obtained before the at least one trip event (such as impedances of the two-port Thevenin equivalent across the transmission line of interest and base impedances of the two-port Thevenin equivalent across the incident transmission line obtained before the at least one trip event) in combination with measurements.
  • impedances obtained before the at least one trip event such as impedances of the two-port Thevenin equivalent across the transmission line of interest and base impedances of the two-port Thevenin equivalent across the incident transmission line obtained before the at least one trip event
  • Model parameters of the line of interest and at least one of the incident line or the shunt element which trips are also used for determining the updated impedances.
  • the measurements required to perform the online update are from within a neighborhood of the transmission line of interest.
  • the measurements that are used for performing the online update may include voltages (and optionally current) at the transmission line of interest, the incident line, the terminal buses of the transmission line of interest, a bus adjacent to the terminal buses of the transmission line of interest, and shunt element currents of the terminal buses of the transmission line of interest and/or the adjacent bus.
  • Current measurements are optional.
  • the measurements that are used for performing the online update may be limited to currents or voltages at the transmission line of interest, the incident line, the terminal buses of the transmission line of interest, a bus adjacent to the terminal buses of the transmission line of interest, and shunt element currents of the terminal buses of the transmission line of interest and/or the adjacent bus.
  • the online update of the equivalent impedances can be performed by a substation device or otherwise at the substation level, without requiring an update from a control center and/or without requiring the full impedance matrix of the complete network to be re-calculated responsive to a topology change.
  • the term "measurement” is to be understood such that it does by no means preclude that processing is performed on the outputs of the sensing devices deployed.
  • “measurements of voltage changes” are intended to encompass voltage changes that are derived computationally from voltage measurements (e.g., as a difference of voltages measured before and after a trip event).
  • the neighborhood of the transmission line of interest from which measurements are used for determining the updated impedances may be limited to the transmission line of interest (also referred to as “first transmission line” herein), its terminal buses, an adjacent bus (also referred to as “third bus” herein), and an incident transmission line (also referred to as “second transmission line” herein), and the associated shunt elements, circuit breakers and/or switches.
  • the updated impedances may be determined without requiring measurements outside that neighborhood.
  • the measurements and/or switch status information may be received in messages in accordance with a substation automation communication protocol, e.g. in messages in accordance with or compatible with IEC 61850.
  • the measurements and/or switch status information may be received in messages in accordance with or compatible with IEC 61850:8-1, IEC 61850:8-2, and/or IEC 61850:9.
  • the measurements and/or switch status information may be received in messages in accordance with or compatible with IEC 61850:8-1 (2011), IEC 61850:8-2 (2016), and/or IEC 61850:9 (2011) and/or IEC 61850:9/AMD1:2020 (2020).
  • determining an impedance is to be understood to encompass the determination of a value that approximates the impedance of an equivalent model. While limiting the use of measurements to measurements available in a neighborhood of the transmission line of interest (such as substation level bus data or measurements) entails some approximations, the devices, systems, and methods according to embodiments provide updated equivalent impedances having a small error only.
  • Figure 1 is a schematic partial representation of an electric power system 10 having a digital substation device 30.
  • the electric power system 10 has a first transmission line 11 between a first bus M and a second bus N.
  • the first transmission line 11 is also referred to as line MN herein, because it extends between buses M and N, or as "transmission line of interest", because the equivalent impedances of this first transmission line are being updated in response to a topology change.
  • the electric power system 10 has a second transmission line 12 between a third bus P and the first bus M.
  • the second transmission line 12 may be any transmission line extending between one of the terminal buses M, N of the first transmission line and a bus P that is adjacent to (e.g., one level up in the network hierarchy) one of the terminal buses M, N of the first transmission line.
  • the second transmission line 12 will also be referred to as "incident line" herein.
  • Shunt elements 21, 22, 23 are provided at the buses P, M, N.
  • the shunt elements 21, 22, 23 may be or may comprise any one or any combination of a reactor, a capacitor bank, a load impedance.
  • the electric power system 10 has breakers 13-19 that may selectively trip.
  • the breakers 13-19 may be operative to provide measurements (such as current measurements) to the substation device 30.
  • the breakers 13-19 may be operative to provide status information (tripped or untripped) to the substation device 30.
  • the substation device 30 may be a digital substation device communicatively coupled to other devices at the substation level.
  • the substation device 30 may be operative to receive and/or transmit data via a substation communication bus.
  • the substation device 30 is operative to determine updated impedances of an equivalent model of the first transmission line 11 responsive to a trip event.
  • the substation device 30 may be operative to determine updated impedances of an equivalent model of the first transmission line 11 responsive to
  • the substation device 30 may be operative to perform updates of impedances of the equivalent model of the first transmission line 11 responsive to other trip events, such as a trip of the shunt element 22 or of the shunt element 23. However, the substation device 30 is preferably operative to at least perform a determination of updated impedances of the equivalent model of the first transmission line 11 in the two scenarios mentioned above.
  • the trip event i.e., the change in network topology in a neighborhood of the first transmission line 11, may trigger the determination of the update process.
  • the updated impedances may be used for any one or any combination of protection or coordination functions, as will be explained in more detail below.
  • All measurements used to determine the updated impedances may be obtained from, e.g., the first and second lines 11, 12 and the buses P, M, N, and the associated switches, circuit breakers, and shunt elements.
  • the following measurements may be used:
  • the following measurements may be used: a shunt current through the shunt element at the third bus P prior to the trip of the shunt element and a change in voltage at the second bus N in response to the trip of the shunt element; optionally measurements of changes in voltages at the first and third buses M, P in response to the trip of the shunt element.
  • the disclosed techniques work without requiring online measurements of other quantities for performing the update of the impedances.
  • the disclosed techniques are operative to determine the updated impedances without requiring or without using current measurements. Currents may be determined computationally.
  • FIG. 2 shows part of the electric power system 10 that is of interest to the update process described in detail herein.
  • the first transmission line 11 between its terminal buses M, N is represented by an equivalent model, and the substation device 30 is operative to determine updated impedances for the equivalent model responsive to trip events.
  • the rest 29 of the electric power system which is shown only schematically, includes various additional transmission lines, buses, etc.
  • the update of the impedance as described herein uses impedance values of the equivalent model that correspond to the untripped system, measurements from only a neighborhood of the first transmission line 11, and topology information from only a neighborhood of the first transmission line 11.
  • the update of the impedance as described herein does not require topology information of parts of the electric power system that are arranged beyond the third bus P and its shunt element(s).
  • Figure 3 shows the two-port Thevenin equivalent across the first transmission line 11.
  • the equivalent system consists of two sources with corresponding impedances Z sM and Z sN . Additionally, a transfer path with impedance Z tr MN may be present which represents equivalent of the network for the current flow between buses M and N except for the direct path through the branch MN itself (which is represented by impedance Z l ).
  • Determining updated impedances for the two-port Thevenin equivalent across the first transmission line 11 comprises determining updated values for ⁇ Z sM , Z sN , Z tr MN ⁇ .
  • Base values of the impedances of the two-port Thevenin equivalent i.e., values for ⁇ Z sM ,Z sN ⁇ Z tr MN ⁇ of the base network (without trip of the second transmission line 12 and without trip of the shunt element at the bus P) are used in determining the updated impedances.
  • the two-port Thevenin equivalent model across the first transmission line 11 is shown in Figure 3
  • the two-port Thevenin equivalent across the second transmission line 12 has similar parameters ⁇ Z sM ,Z sP , Z tr MP ⁇ .
  • the substation device 30 may be operative to use
  • Thevenin equivalent across the second transmission line 12 obtained before the at least one trip event are impedance values obtained from a full network analysis (i.e., including the parts of the electric power system connected beyond the buses shown in Figures 1 to 3 ).
  • the device or system that determines the updated impedances during field operation may receive the impedances of the untripped system (or base impedances) as an input. This input does not need to be re-received when the impedances are re-determined several times during field operation, respectively in response to trip events.
  • the impedances of the untripped system (or base impedances) may be persistently stored in the device or system that determines the updated impedances in field operation.
  • first modified impedances during field operation in response to a first trip event such as a first incident line trip or a first shunt element trip
  • second updated impedances during field operation in response to a second trip event such as a second incident line trip or a second shunt element trip
  • first trip event such as a first incident line trip or a first shunt element trip
  • second trip event such as a second incident line trip or a second shunt element trip
  • the updated values of the two-port Thevenin equivalent impedances can then be used as base impedances for any subsequent impedance update determinations (if needed).
  • a user or operator may obtain the impedances of the untripped system (or base impedances) as a one-time exercise from a control center (which may be a regional or main control center), which based on its access to the entire network topology data shall be capable of calculating them.
  • Retrieval of the impedances of the untripped system (or base impedances) and providing them to the device or system that determines updated impedances may be done prior to field operation (e.g., during commissioning of an IED or system that determined the updated impedances, such as during commissioning of a substation) or during system maintenance after the device or system has entered field operation.
  • Updated values of the two-port Thevenin equivalent impedances (post a trip event) determined during field operation can then be used as base impedances for any subsequent updations (if needed).
  • the substation device 30 determines updated values for the impedances ⁇ Z sM ,Z sN , Z tr MN ⁇ of the two-port Thevenin equivalent across the first transmission line 11.
  • the updated impedances can be used for various purposes, including analysis, protection, and/or coordination functions.
  • the updated impedances can be used for any one or any combination of:
  • Figure 4 is a block diagram of a substation device or system 30 according to an embodiment.
  • the substation device or system 30 has a first interface 38 operative to receive a measurements and, optionally, other data.
  • the first interface 38 may be operative for communicative coupling to breakers to receive breaker status information and current measurements.
  • the first interface 38 may be operative for communicative coupling to breakers to receive breaker status information and current measurements.
  • the first interface 38 may be operative to receive measurements of a voltage at the second bus N prior to and subsequent to a trip event, or other measurements that allow the substation device or system 30 to determine the change in voltage at the second bus N responsive to the trip event.
  • the first interface 38 may be operative to receive charging currents for the second transmission line 12 prior to a trip of the second line 12 or other measurements that allow the allow the substation device or system 30 to determine the charging currents for the second transmission line 12 prior to the trip of the second line 12.
  • the substation device or system 30 may be operative to process these measurements to determine updated impedances responsive to a trip of the second transmission line 12.
  • the first interface 38 may be operative to receive a shunt element current through the shunt element 21 prior to trip of the shunt element 21.
  • the substation device or system 30 may be operative to process these measurements to determine updated impedances responsive to a trip of the shunt element 21.
  • the first interface 38 may optionally be operative to receive measurements of voltages at the first and third buses M, P prior to and subsequent to a trip event, or other measurements that allow the substation device or system 30 to determine the change in voltages at the first and third buses M, P responsive to a trip event.
  • the substation device or system 30 has one or several integrated circuits (IC(s)) 31 that perform processing functions.
  • the one or several IC(s) 31 may include one or several of a processor, a microprocessor, a controller, a microcontroller, a field-programmable gate array (FPGA), an application specific integrated circuit (ASIC) or any combination thereof.
  • the IC(s) 31 are operative to implement an impedance update module 32.
  • the impedance update module 32 may determine updated values for the impedances ⁇ Z sM ,Z sN , Z tr MN ⁇ of the two-port Thevenin equivalent across the first transmission line 11 responsive to a trip event, using any one of the processing techniques disclosed herein.
  • the IC(s) 31 may be operative to implement an analysis, protection, or coordination function 33. This function may also be implemented separately from the substation device 30.
  • the analysis, protection, or coordination function 33 may be operative to perform a protection function, in particular a distance protection function.
  • the analysis, protection, or coordination function 33 may be operative to perform various functions, such as any one or any combination of: adaptive settings (in particular for adaptive distance relaying), performing single ended fault location determination, calculating the system non-homogeneity factor, distance relay reach calculation, adaptive switching the different phase selection methods (phasor or super imposed quantities or traveling wave based) to protect systems with high renewables, calculation of short circuit ratio (SCR), over current relay co-ordination.
  • adaptive settings in particular for adaptive distance relaying
  • SCR short circuit ratio
  • the IC(s) 31 may be operative to issue signals or commands via at least one second interface 39 to cause a determined action to be taken, a determined setting to be applied, or determined information to be output.
  • the IC(s) 31 may be operative to implement an output generation module 34.
  • the output generation module 34 may cause output (alarms, warning, notifications, or other information) to be output to an operator, e.g., to a substation operator.
  • Information on the impedances ⁇ Z sM ,Z sN , Z tr MN ⁇ of the equivalent model across the first transmission line 11 obtained before the at least one trip event, on the line impedance Z l of the direct connection MN (see Figure 3 ), and, where applicable, on the on the impedances ⁇ Z sM ,Z sP , Z tr MP ⁇ of the equivalent model across the second transmission line 12 obtained before the at least one trip event, on the line impedance Z l of the direct connection MP (note that this impedance may be different from the line impedance of the direct connection MN), and on the impedance of the shunt element(s) that can trip may be stored in a storage device 35 and may be retrieved therefrom for processing by the IC(s) 31.
  • the storage device 35 may be integrated in the substation device 30 or may be provided separately therefrom.
  • Figure 5 is a flow chart of a method 40.
  • the method 40 may be performed automatically by the substation device or system 30.
  • the measurements may comprise voltage measurements.
  • the voltage measurements may comprise a change in voltage at one or several of the buses N, M, and P responsive to a trip event. Determination of the change in voltage may be performed by the substation device or system 30 or by a separate entity.
  • the impedance submatrix may be a 3 ⁇ 3 matrix.
  • the impedance submatrix may be a 3 ⁇ 3 submatrix of the bus impedance matrix.
  • Some of the matrix elements of the impedance submatrix may be determined from the impedance values ⁇ Z sM ,Z sN , Z tr MN ⁇ of the two-port Thevenin equivalent across the first transmission line 11 obtained before the at least one trip event. At least one of the matrix elements of the impedance submatrix may be determined using the received measurements.
  • the remaining matrix elements of the impedance submatrix may be determined from the impedances ⁇ Z sM ,Z sP , Z tr MP ⁇ of the two-port Thevenin equivalent across the second transmission line 12 obtained before the at least one trip event or using the received measurements.
  • step 43 updated impedances ⁇ Z sM ,Z sN , Z tr MN ⁇ of the two-port Thevenin equivalent across the first transmission line 11 are determined, using the impedance submatrix determined at step 42.
  • output is generated based on the updated impedances to perform an analysis, protection, and/or coordination function.
  • the method may comprise performing an analysis, protection, and/or coordination function.
  • the analysis, protection, and/or coordination function may comprise any one or any combination of adaptive settings (in particular for adaptive distance relaying), performing single ended fault location determination, calculating the system non-homogeneity factor, distance relay reach calculation, adaptive switching the different phase selection methods (phasor or super imposed quantities or traveling wave based) to protect systems with high renewables, calculation of short circuit ratio (SCR), over current relay co-ordination.
  • the device or method requires online information from only a neighborhood of substation level measurements to provide an online update of the two-port equivalent.
  • the device or method use information of lines and buses adjacent to the line of interest, i.e., network information of the adjacent topology, to update the two-port equivalent model across the line of interest.
  • the effect of topology changes in the neighborhood of the line of interest can be accounted for by updating its two-port equivalent.
  • the device or method consider tripping-off of the line 12 incident on one of the terminal buses M of the line 11 of concern or tripping-off of a shunt element 21 (reactor/capacitor) at a bus P one level up (i.e. an adjacent bus) in the topology.
  • the device or method perform the update of the impedances without requiring the bus impedance matrix Z BUS of the full electric power system 10 to be updated and uses only local update information which may be available as substation process bus level measurements and data.
  • This local measurements and data may be the bus voltage measurements at both ends of the line of concern, currents on the lines incident on the terminal buses, currents through the connected shunt elements and model parameters of the line and the neighboring elements, i.e.
  • the device or method may utilize measurements related to the switching event and parameters of the line of concern and the tripped element for updating the two-port equivalent. Current measurements are optional. For illustration, currents may also be computed, as explained in more detail herein.
  • the device or method may utilize digital substation measurements at both ends of the transmission line 11 and substations one level up in the network.
  • the substation device 30 has access to measurements from the substations M, N and P.
  • the symbol P is indicative of any bus one level up in the network topology with respect to the line of interest 11.
  • Model parameters of the line of interest and all incident elements are also available to the substation device 30.
  • the device or method may determine or otherwise process matrix elements of an impedance submatrix.
  • the impedance submatrix may be a submatrix of the full impedance matrix Z bus of the electric power network.
  • the device or method may process one or several of the following submatrices of the bus impedance matrix Z bus of the full electric power network:
  • Z mnp Z mm Z mn Z mp Z nm Z nn Z np Z pm Z pn Z pp
  • Z mnp ⁇ Z mm ⁇ Z mn ⁇ Z mp ⁇ Z nm ⁇ Z nn ⁇ Z np ⁇ Z pm ⁇ Z pn ⁇ Z pp ⁇
  • Z mnp ⁇ Z mm ⁇ Z mn ⁇ Z mp ⁇ Z nm ⁇ Z nn ⁇ Z np ⁇ Z pm ⁇ Z pn ⁇ Z pp ⁇ .
  • Z ( mnp ) represents the impedance submatrix bus impedance matrix Z bus of the full electric power network which consists of only the nine elements corresponding to nodes M, N and P.
  • the impedance submatrix Z ( mnp )' corresponds to the network from which the branch between node M and N is removed.
  • the impedance submatrix Z ( mnp )" corresponds to the network from which the branch between nodes M and N and the tripped element are removed.
  • Z ( mnp ) is the impedance submatrix of the of the Z bus of the network without the line between buses M and N and the line between buses M and P.
  • Z sM Z mm ⁇ Z nn ⁇ ⁇ Z mn ⁇ Z nm ⁇ Z nn ⁇ ⁇ Z mn ⁇
  • Z sN Z mm ⁇ Z nn ⁇ ⁇ Z mn ⁇ Z nm ⁇ Z mm ⁇ ⁇ Z mn ⁇
  • Z tr MN Z mm ⁇ Z nn ⁇ ⁇ Z mn ⁇ Z nm ⁇ Z mn ⁇ .
  • the device or method can establish the impedance submatrix Z ( mnp )" and can determine the updated impedances of the two-port equivalent model of the transmission line 11 using Equation (4).
  • Z ( mnp ), Z ( mnp )' and Z ( mnp ) " are related. This is because Z ( mnp )' can be obtained from Z ( mnp ) by performing series and shunt branch (corresponding to the series impedance and shunt admittances of line MN) modifications on Z ( mnp ).
  • the network impedance submatrix Z ( ijk ) corresponding to nodes i, j and k is given by Equation (5) below.
  • Z ijk Z ii Z ij Z ik Z ji Z jj Z jk Z ki Z kj Z kk
  • the substation device or method according to an embodiment obtains the impedance submatrix elements Z mm ⁇ , Z nn ⁇ , and Z mn ⁇ , the elements Z mm , Z mn , Z nm and Z nn can be obtained by carrying out the modification calculations on Z ( mn )' pertaining to addition of the line MN between buses M and N as explained with reference to Equation (6).
  • the substation device or method according to an embodiment can obtain Z mp , Z pm and Z pp following the same procedures.
  • the substation device or method can obtain all elements of Z ( mnp ) except for Z np and Z pn if the initial parameter sets of ⁇ Z sM ,Z sN , Z tr MN ⁇ and ⁇ Z sM ,Z sP , Z tr MP ⁇ are accessible (e.g., from storage device 35).
  • the substation device or method are operative to obtain Z np and Z pn from the available substation measurements.
  • Z np Z pn .
  • Figure 7 is a flow chart of a method 50. The method may be performed automatically by the device 30.
  • matrix elements of the bus impedance submatrix Z are obtained.
  • the matrix elements may be obtained from the initial parameter set of ⁇ Z sM ,Z sN , Z tr MN ⁇ and, optionally, ⁇ Z sM ,Z sP , Z tr MP ⁇ , and parameters of the line(s) (such as shunt impedances).
  • the impedance submatrix Z ( mnp )" is determined from the impedance submatrix Z ( mnp ) by performing modification computations (Equations (6) and (7)).
  • the updated parameter set of ⁇ Z sM ,Z sN , Z tr MN ⁇ is determined from the impedance submatrix Z ( mnp )" in accordance with Equation (4).
  • the method may further comprise performing an analysis, protection, or coordination function based on the updated parameter set of ⁇ Z sM ,Z sN , Z tr MN ⁇ .
  • the impedance submatrix Z ( mnp )' corresponds to the network from which the line MP is removed from the base network.
  • the impedance submatrix Z ( mnp )" corresponds to the network from which the line MN is also removed. Note that the elements of Z ( mnp )" will remain the same as before, because only the sequence of removal of lines from the base network is changed.
  • the current flow on the line MP can be considered as current injections at buses M and P of the system without the line MP physically present in the network as depicted in Figure 9 .
  • I mp and I pm are load currents of the line MP.
  • I mc is a charging current of line MP at bus M.
  • I mp is a charging current of line MP at bus P.
  • I mc is a charging current of the second line at the first bus before the trip of the second line (which may be calculated)
  • I pc is a charging current of the second line at the second bus before the trip of the second line (which may be calculated)
  • I mp + I mc is a current measured on the second line at the first bus before the trip of the second line (which may be measured or computationally derived from measurements).
  • the elements of submatrix Z ( mnp )' are related to the elements of Z ( mnp ) by means of series and shunt branch modifications pertaining to the line MP.
  • the right-hand side of the expression (9) can be written completely in terms of elements of Z ( mnp ). This results in an equation with Z pn as the variable since the quantity on the left-hand side can be obtained from measurements
  • the currents that are calculated may be calculated as explained above with reference to Equations (E1) and (E2).
  • At least Z mp , Z pm , and Z pp may be determined using impedances of the equivalent model of the two-port equivalent obtained before the at least one trip event and modification calculations (Equation (6)).
  • the device or method according to an embodiment can determine the updated impedance values for an incident line trip as follows:
  • Figure 8 is a flow chart of a method 60. The method may be performed automatically by the device 30.
  • the matrix elements may be obtained from the initial parameter set of ⁇ Z sM ,Z sN , Z tr MN ⁇ , the line impedance Z l of the line MN, and the modification calculations of Equation (6).
  • the matrix elements may be obtained from the initial parameter set of ⁇ Z sM ,Z sP , Z tr MP ⁇ . and parameters of the line MP (such as its line impedance Z l t ).
  • the updated parameter set of ⁇ Z sM ,Z sN , Z tr MN ⁇ is determined. This may comprise determining the impedance submatrix Z ( mnp )" from the impedance submatrix Z ( mnp ) by performing modification computations (Equations (6) and (7)), and determining the updated parameter set of ⁇ Z sM ,Z sN , Z tr MN ⁇ from the impedance submatrix Z ( mnp )" in accordance with Equation (4).
  • the method may further comprise performing an analysis, protection, or coordination function based on the updated parameter set of ⁇ Z sM ,Z sN , Z tr MN ⁇ .
  • I mc is a charging current of the second line at the first bus before the trip of the second line (which may be calculated)
  • I pc is a charging current of the second line at the second bus before the trip of the second line (which may be calculated)
  • I mp + I mc is a current measured on the second line at the first bus before the trip of the second line (which may be measured or computationally derived from measurements).
  • the currents that are calculated may be calculated as explained above with reference to Equations (E1) and (E2).
  • Equations (9), (11) and (12) can be approximated as follows: ⁇ V n I mp + I mc ⁇ Z mn ⁇ ⁇ Z pn ⁇ , ⁇ V m I mp + I mc ⁇ Z mm ⁇ ⁇ Z pm ⁇ , ⁇ V p I mp + I mc ⁇ Z mp ⁇ ⁇ Z pp ⁇ .
  • Equations (13) and (14) can be solved simultaneously to obtain (Z mm - Z mp ), ( Z nm - Z np ) and ( Z pm - Z pp ) as shown in (15) below.
  • Z mm ⁇ Z mp ⁇ ⁇ V m I mp + I mc
  • Z nm ⁇ Z np ⁇ ⁇ V n I mp + I mc
  • Z pm ⁇ Z pp ⁇ ⁇ V p I mp + I mc
  • 1 ⁇ 1 + 1 ⁇ ⁇ V p ⁇ V m ⁇ V m I mp + I mc / Z l t
  • the device or method according to embodiments can obtain Z mp , Z np and Z pp without requiring the equivalent impedance parameters of Line MP before the trip event.
  • this technique provides an alternative to the solution described with reference to Equation (10) above.
  • the present technique is based on the simplifying approximation that charging current of Line MP is negligible in comparison to the line loading current.
  • the device or method according to an embodiment can determine the updated impedance values for an incident line trip as follows:
  • Figure 11 is a flow chart of a method 70. The method may be performed automatically by the device 30.
  • the matrix elements may be obtained from the initial parameter set of ⁇ Z sM ,Z sN , Z tr MN ⁇ , the line impedance Z l of the line MN, and the modification calculations of Equation (6).
  • the updated parameter set of ⁇ Z sM ,Z sN , Z tr MN ⁇ is determined. This may comprise determining the impedance submatrix Z ( mnp ) " from the impedance submatrix Z ( mnp ) by performing modification computations (Equations (6) and (7)), and determining the updated parameter set of ⁇ Z sM ,Z sN , Z tr MN ⁇ from the impedance submatrix Z ( mnp )" in accordance with Equation (4).
  • the method may further comprise performing an analysis, protection, or coordination function based on the updated parameter set of ⁇ Z sM ,Z sN , Z tr MN ⁇ .
  • the test system considered is IEEE 39 bus NETS-NYPS system (Manitoba HVDC Research Centre, IEEE Test Systems, available at: http:Hforum.hvdc.ca/1598644/IEEE-Test-Systems).
  • the single line diagram is shown in Figure 16 .
  • the method explained with reference to Figures 7 to 10 (including use of Equation (10)) is used to update the two-port equivalent for Line 17-16 in Figure 16 .
  • the base equivalent impedance parameters are obtained by complete network analysis approach of the base network. The obtained results are compared with the equivalent obtained by complete network analysis of the modified network. A step-by-step analysis is shown below.
  • Figure 13 is a flow chart of a method 80. The method may be performed automatically by the device 30.
  • matrix elements of the bus impedance submatrix Z are obtained.
  • the matrix elements may be obtained from the initial parameter set of ⁇ Z sM ,Z sN , Z tr MN ⁇ and, optionally, ⁇ Z sM ,Z sP , Z tr MP ⁇ , and parameters of the line(s) (such as shunt impedances).
  • the impedance submatrix Z ( mnp )" is determined from the impedance submatrix Z ( mnp ) by performing modification computations (Equations (6) and (7)).
  • the modification computations comprise removing the shunt element 22 at bus P and first line 11 between buses M and N.
  • the updated parameter set of ⁇ Z sM ,Z sN , Z tr MN ⁇ is determined from the impedance submatrix Z ( mnp )" in accordance with Equation (4).
  • the method may further comprise performing an analysis, protection, or coordination function based on the updated parameter set of ⁇ Z sM ,Z sN , Z tr MN ⁇ .
  • the impedance submatrix Z ( mnp ) ' corresponds to the network from which the shunt element at bus P (of impedance Z sh ) is removed from the base network.
  • the impedance submatrix Z ( mnp )" corresponds to the network from which the line MN is also removed.
  • the current flow on the shunt element at bus P I p sh can be considered as a current injection at bus P of the system without the shunt element physically present in the network. Therefore, tripping of the shunt element 22 can be considered as a change in current injections at bus P for the system without the shunt element at bus P.
  • Z pn ⁇ can be obtained from measurements of voltage drop at bus N due to the shunt element trip at bus P and the current carried by the shunt element before it tripped.
  • the current I p sh may be directly measured.
  • the device or method according to an embodiment can determine the updated impedance values for an incident line trip as follows:
  • Figure 14 is a flow chart of a method 90. The method may be performed automatically by the device 30.
  • the matrix elements may be obtained from the initial parameter set of ⁇ Z sM , Z sN , Z tr MN ⁇ , using the modification calculations of Equations (6) and (7).
  • the matrix elements may be obtained from the initial parameter set of ⁇ Z sM ,Z sP , Z tr MP ⁇ . using the modification calculations of Equations (6) and (7).
  • the updated parameter set of ⁇ Z sM ,Z sN , Z tr MN ⁇ is determined. This may comprise determining the impedance submatrix Z ( mnp )" from the impedance submatrix Z ( mnp ) by performing modification computations (Equations (6) and (7)), and determining the updated parameter set of ⁇ Z sM ,Z sN , Z tr MN ⁇ from the impedance submatrix Z ( mnp )" in accordance with Equation (4).
  • the method may further comprise performing an analysis, protection, or coordination function based on the updated parameter set of ⁇ Z sM ,Z sN , Z tr MN ⁇ .
  • the device and method may determine the updated impedances of the two-port equivalent without requiring information on the impedances of the two-port equivalent across line MP before the trip event.
  • Z mp and Z pp can also be determined from measurements.
  • Z pp ⁇ ⁇ V p I p sh
  • Z pp ⁇ Z pp ⁇ Z sh
  • Z pp ⁇ Z pp ⁇ Z sh
  • Z pm ⁇ ⁇ V m I p sh
  • Z mp ⁇ Z mp ⁇ Z sh Z pp ⁇ Z sh
  • the device and method may use Equation (18) to determine Z pp .
  • the obtained value of Z pp can be used to solve Equations (17) and (18) for Z mp and Z np respectively.
  • the updated source impedances can be obtained with fewer base information, specifically without requiring the impedances of the two-port equivalent across line MP before the trip event.
  • the device and method require measurements from buses P and M in response to the shunt element trip.
  • the device or method according to an embodiment can determine the updated impedance values for an incident line trip as follows:
  • Figure 15 is a flow chart of a method 100. The method may be performed automatically by the device 30.
  • the matrix elements may be obtained from the initial parameter set of ⁇ Z sM , Z sN , Z tr MN ⁇ and the modification calculations of Equations (6), (7).
  • the updated parameter set of ⁇ Z sM ,Z sN , Z tr MN ⁇ is determined. This may comprise determining the impedance submatrix Z ( mnp )" from the impedance submatrix Z ( mnp ) by performing modification computations (Equations (6) and (7)), and determining the updated parameter set of ⁇ Z sM ,Z sN , Z tr MN ⁇ from the impedance submatrix Z ( mnp )" in accordance with Equation (4).
  • the method may further comprise performing an analysis, protection, or coordination function based on the updated parameter set of ⁇ Z sM ,Z sN , Z tr MN ⁇ .
  • the test system considered is IEEE 39 bus NETS-NYPS system ( Figure 16 ).
  • Line MN 5-8
  • Line MP 5-6
  • the technique explained above is applied to update the two-port equivalent for Line 5-8.
  • the base equivalent impedance parameters are obtained by complete network analysis approach of the base network (shunt reactor at bus 6 considered to be present). The obtained results are compared with the equivalent obtained by complete network analysis of the modified network.
  • the updated equivalent model can be used for various analyses, protection and/or coordination functions. For example, it can be used for setting the operational characteristics of a distance relay protecting the transmission line of interest and for determining the source to line impedance ratio (SIR) for the relay, using, for example, the techniques described in "IEEE Guide for Protective Relay Applications to Transmission Lines," in IEEE Std C37.113-2015 ( Revision of IEEE Std C37.113-1999), pp.1-141, 30 June 2016 .
  • the updated model can also be used for setting the power swing blinders and out of step logic, using, for example, the techniques described in " POWER SWING AND OUT-OF-STEP CONSIDERATIONS ON TRANSMISSION LINES", IEEE PSRC WG D6, 2005, pp.
  • the updated model can help analyses such as locating a fault on the line when using only single ended measurements, using, for example, the techniques described in L. Eriksson, M. M. Saha and G. D. Rockefeller, "An Accurate Fault Locator with Compensation for Apparent Reactance in The Fault Resistance Resulting from Remote-End Infeed," in IEEE Transactions on Power Apparatus and Systems, vol. PAS-104, no. 2, pp. 423-436, Feb. 1985 .
  • the parameters of the two-port equivalent depend on the network topology.
  • the devices, systems, and methods according to embodiments of the invention allow the parameters of the two-port equivalent to be updated online as the network topology changes, without requiring the bus impedance matrix of the full network to be re-calculated.
  • the techniques disclosed herein may be performed by a substation device 30 that is a protection device.
  • the device 30 that determines the updated impedances of the two-port equivalent across a transmission line may be communicatively coupled to protection relays 121, 122, fault localization devices 123, and/or other elements of a substation system 120, as illustrated in Figure 17 .
  • the substation device 30 may be communicatively coupled to the protection relays 121, 122, fault localization devices 123, and/or other elements of a substation system 120 via a substation communication bus.
  • FIG 18 is a schematic diagram of an electric power system 130.
  • the electric power system 130 has a plurality of substations 131-133, each comprising a substation device or system 141-143 operative to determine updated impedances of a two-port equivalent model using the techniques disclosed herein.
  • the electric power system 130 may comprise a central entity 150 communicatively coupled to the substation devices or systems 141-143.
  • the central entity 150 may be operative to coordinate the substation devices or systems 141-143.
  • the central entity 150 may be operative to combine updated impedances obtained from different substation devices or system 141-143.
  • the substation devices or systems 141-143 may be operative to update equivalent impedances independently of each other.
  • a first substation device or system 141 may be operative to update impedances using measurements of the associated first substation 131 and, optionally, an adjacent bus and incident line responsive to a first trip event.
  • a time at which the first substation device or system 141 determines the updated impedances may be independent of a time at which any of the other substation devices or system 142, 143 (e.g., a second substation device or system 142 of a second substation 132 and/or a third substation device or system 143 of a third substation 133) determines updated impedances.
  • the impedances of the first, second and, if present, additional substation devices or systems 141-143 as updated during field operation may be updated at times and/or to values that are independent of each other.
  • the central entity 150 may be operative to receive updated impedances from the substation devices or systems 141-143.
  • the central entity 150 may be operative to combine updated impedances from the substation devices or systems.
  • the central entity 150 may be operative to update a bus matrix, using the updated impedances from the substation devices or systems 141-143.
  • the central entity 150 may be operative to coordinate operation of the substation devices or systems 141-143 of different substations.
  • the central entity 150 and/or the substation devices or systems 141-143 may be operative to use the updated impedances for analyses, protection and/or coordination functions.
  • the central entity 150 and/or the substation devices or systems 141-143 may be operative to use the updated impedances for one or several of: setting operational characteristics of a distance relay, setting power swing blinders and/or out of step logic, locating a fault on the line (e.g., when using only single ended measurements, or for other techniques of performing fault localization).
  • Embodiments of the invention provide a device, system and method for updating the two-port Thevenin equivalent across a transmission line.
  • the devices and method may be operative for collating data and measurements from the line terminals and substations one level up in the topology in order to update the equivalent model when a topological change happens in the vicinity of the line of interest.
  • the scenarios considered are tripping of an incident line and tripping of a shunt element at an adjacent bus.
  • Various solutions are provided which correspond to these scenarios.
  • the device, system and method can be implemented in a digital substation for supporting adaptive protection features, without being limited thereto.
  • the devices, methods, and systems according to embodiments may be used to provide improved distance protection for transmission networks in which the lines may have a length of at least 50 km, of at least 100 km, of at least 150 km, of at least 200 km, without being limited thereto.
  • the devices, methods, and systems according to embodiments may be used for performing a wide variety of different protection, monitoring, and/or analysis functions for an electric power system.
  • a protection function and/or the generation of an output may be automatically triggered, using the updated impedances.
  • the devices, methods, and systems according to embodiments may be used to provide distance protection for transmission networks in an electric grid that includes renewable energy sources.

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EP21160638.9A 2021-01-19 2021-03-04 Dispositif, système et procédé pour effectuer une mise à jour en ligne d'un équivalent à deux ports Pending EP4030573A1 (fr)

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